Measurements of direct photons in Au+Au collisions with PHENIX

Abstract

The PHENIX experiment has published direct photon yields and elliptic flow coefficients $v_2$ from Au+Au collisions at RHIC energies. These results have sparked much theoretical discussion. The measured yields and flow parameters are difficult to reconcile in current model calculations of thermal radiation based on hydrodynamic time evolution of the collision volume. Our latest analyses which use high statistics data from the 2007 and 2010 runs allow the determination of direct photon yields with finer granularity in centrality and photon momentum and down to $p_T$ as low as 0.4 GeV/$c$. We will summarize the current status and present new results from PHENIX.